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The Arctic experienced an extended time period of warm temperatures about 3.6 million age ago — before the onslaught of the chalk ages — at a prison term when the tightness of carbon dioxide in Earth ’s atmosphere was not much eminent than the story being register today , a new subject area finds . The research suggest that an ice - free Arctic may be a reality in the near future .
An international squad of researchers analyzed deposit substance pick up in 2009 from Lake El’gygytgyn ( judge El - Gee - Git - Kin ) , the oldest mysterious lake in the northeast Russian Arctic . The samples activate the scientist to peer back into theArctic ’s climate historydating from 2.2 million to 3.6 million years ago , during the middle Pliocene and former Pleistocene epochs .
Multi-year Arctic ice in 2012. The bright white central mass shows the perennial sea ice. The larger light blue area shows the full extent of the winter sea ice including the average annual sea ice during the months of November, December and January.
The research worker get that during this clip , the Arctic was very fond , with summertime temperatures about 14 degrees Fahrenheit ( 8 degrees Celsius ) warm than they are in the region today , said Julie Brigham - Grette , a professor in the department of geosciences at the University of Massachusetts Amherst and lead generator of the new study , which was published today ( May 9 ) in the journal Science .
" There was probably no ocean icing , and the whole Arctic was somewhat well forested , so it was a very different world , " Brigham - Grette secernate LiveScience . " So , how did we go from that to the tundra that we have today , and what does this secernate us about the future ? " [ Images of Melt : Earth ’s Vanishing Ice ]
A windowpane into the yesteryear
Study co-authors Julie Brigham-Grette and Pavel Minyuk collect sediment cores from Lake El’gygytgyn in the northeast Russian Arctic. These samples help scientists better understand the Arctic’s climate history, dating from 2.2 million to 3.6 million years ago
Lake El’gygytgyn , or " Lake E , " as the investigator refer to it , was formed 3.6 million year ago whena meteorite hit Earthand cut up out an 11 - mile - across ( 18 kilometers ) crater . The lake is one of the few Arctic areas not eroded bycontinental ice sheetsduring the chicken feed ages , meaning it has collected a uninterrupted and undisturbed deposit record , the researchers said .
The lake , which today is cover in chalk for most of the year , is so thick that if the Washington monument were place inside it , the tip would just scarce come out above the surface , Brigham - Grette said .
The researchers examined fossil pollen in the sediment core and discovered vestige of Douglas fir and poison parsley . Understanding the vegetation in the area during that time helped the scientists piece together more clue about the precipitation and climate .
" To get Douglas fir and poison hemlock that far northward of the Arctic Circle — you have to have pretty affectionate summers and warm winters in gild for those trees to establish there , " Brigham - Grette said .
premature research suggests the proportion of carbon dioxide ( CO2 ) in the atmosphere in theMiddle Plioceneand Early Pleistocene was similar to the layer that are recorded today and assign to humanity - made germ . If this is the vitrine , Earth ’s climate may be more sensible to carbon dioxide than scientist antecedently thought , Brigham - Grette allege .
" We can see that the Arctic is quite sensitive to CO2 change , and levels in the Pliocene were thought to be similar to today , " Brigham - Grette explain . " Some of the changes we see going on now — sea glass melting , tree lines migrating and glacier with tremendous ablation charge per unit — suggest that we ’re heading back to the Pliocene . "
rise greenhouse gases
Climate scientists are expecting the atmospherical carbon dioxide story toexceed 400 parts per millionany day now , which will break a 3 - million - class record . Hitting that level means there are 400 particle of carbon dioxide in the air for every 1 million tune corpuscle .
" We want to love these mechanisms so we can understand better if the clime system has material , serious tipping points , " Brigham - Grette said . " As we get tender , is there a tipping point where the mood would careen into a different sort of government that we would be upset about ? Understanding the past helps inform us of what the future might curb for us . " [ Earth in the counterweight : 7 Crucial Tipping Points ]
The results of this young cogitation represent an important contribution toward interpret how Earth is affected byman - made greenhouse gas , said Kate Moran , an sea engineer who was not involved with the study . Moran is theater director of NEPTUNE Canada , an submersed sea observatory managed by the University of Victoria in British Columbia .
" This new paleoclimate criminal record adds to the grow evidence that Earth ’s sensitivity to these levels of greenhouse gases may be higher than antecedently thought , " Moran said . " Understanding Earth ’s sensitiveness is one of the key parameter for predicting next stipulation of the planet under global heating . "
And a return to Pliocene - type atmospheric condition may not be too far off in the time to come , said Gifford Miller , a prof in the section of geological science at the University of Colorado Boulder , who impart research in the Canadian Arctic .
" The ice is melting at all elevations , " Miller say . " Even if there is no extra warming , it ’s only a matter of time before the ice is all gone . "
rethink the timeline
The extended strong full point during the middle Pliocene also raises new doubt about the subsequent glass ages . According to the Modern bailiwick , fond Arctic temperaturespersisted past the time when old studies estimated the start of expanding glacier in the Northern Hemisphere , Moran said .
These conflicting results mean scientists are still unclear when big continental glass sheets get to expand and develop , and what triggered these changes .
" It really stays relatively warm in the Arctic , even in the onset of the first part of the trash years cycles/second , " Miller said . " That one was unexpected . "
But , investigator are tardily fill in the history of the Arctic ’s mood , say Brigham - Grette .
" I care to guess of it as working on a big 500 - art object puzzle , " she said . " We had 200 piece before , and now the lake record book bring home the bacon us with another 100 pieces , and the picture is take up to become more and more clear . "
